The present invention relates to a food product processing apparatus for processing food product, a food product transport mechanism, a lift used to remove food product from the apparatus, and a method of operating the apparatus, and more particularly to a food product transport mechanism for a food product processing apparatus that has a perforate lift that possesses improved dewatering capabilities.
Commercial food processing equipment, such as blanchers, steamers, cookers, and coolers, have been used to process food product, such as pasta, vegetables, meats, sauces, juices, pastes, mixed food product, pouched food product, noodles, macaroni, and other types of food product in large quantities. Such food processing equipment usually utilizes a tank equipped with an inlet through which food product to be processed enters. A food product transport mechanism in the tank moves the food product along the tank from adjacent the inlet to adjacent an outlet where a lift is used to remove food product by delivering it to a discharge. The tank typically holds a fluid heat transfer medium that contacts the food product in the tank to process the food product by changing its temperature to heat or cool the food product.
Types of food processing equipment used to process food product using a heat transfer medium include blanchers, cookers, cooker-coolers, and steamers. A rotating auger is a preferred type of food product transport mechanism used in such equipment to urge food product from adjacent the inlet end of the tank toward the discharge end. The auger is equipped with at least one lift located adjacent the discharge to scoop up and discharge food product from the tank. The lift typically comprises one or more perforate lift buckets. In many instances, the auger is equipped with several such lift buckets. While in the tank, a liquid heat transfer medium typically is used to heat the food product. The rate of rotation of the auger is selected to control the amount of time the food product resides in the tank, i.e., residency time, to help achieve a desired amount of processing.
Other types of food processing equipment are used to process food product by removing heat. For example, chillers and coolers are often used to cool food product, such as after it has been heated, so that the food product can be more quickly frozen or packaged for shipment. The food product transport mechanism, which typically also is an auger, urges food product along the tank until it is discharged by the lift. The heat transfer medium used to cool the food product typically also is a liquid.
Each lift bucket is made from a flat sheet of metal, typically of 16 gauge stainless steel, that is punched or laser cut to create several sets of dewatering perforations in it. In one known prior art lift bucket depicted in FIG. 2, each such perforation is oval in shape, extends completely through the sheet, and has a width of about xe2x85x9 inch and a length of about xc2xe inch such that the total open area of the perforations is no more than 18% of the total bucket surface area. Lift buckets of this construction having perforations with a width of {fraction (1/16)} of an inch or {fraction (5/32)} of an inch have also been used. The bucket also has a bend that helps contour the bucket so it facilitates discharge of the food product. An angled or inclined flange is attached to a bucket side edge to help guide food product into the bucket. The other bucket side edge is attached to an endwall of the auger located adjacent the discharge. As the lift bucket scoops up food product, the perforations dewater food product by permitting liquid heat transfer medium on the food product and on the bucket to pass through the bucket and return to the tank. By preventing loss of heat transfer medium out the tank discharge, less makeup liquid processing medium must be added to the tank during operation which thereby also reduces the energy that must be expended to heat or cool the fluid in the tank to keep it at a desired temperature.
Unfortunately, there is an auger rotational speed limit above which all of the liquid scooped up by such a prior art perforated bucket will not pass through the perforations before the bucket reaches the discharge position. This typically happens at an auger speed of between about 3 to 4 revolutions per minute (RPM), depending on the type of food product. When this happens, some of the liquid food product processing medium remains in the bucket and on food product in the bucket when the food product is discharged. As a result, some of the liquid also ends up being discharged.
When liquid food product processing medium is lost, it must be replaced. Energy must be expended to pump makeup liquid into the tank and to heat or cool the liquid until it corresponds to a desired tank temperature, all of which increases operating costs. Additionally, the auger cannot be rotated much faster than this speed limit without the buckets essentially pumping even larger amounts of liquid out the discharge. As a result, each food processing machine equipped with the aforementioned prior art lift buckets has a rotational speed limit that undesirably limits its food product processing throughput.
Unfortunately, it is believed that there is little room, if any, to improve the dewatering capacity of the prior art lift buckets. Increasing dewatering capacity is not as simple as adding more perforations or increasing the size of each perforation. Increasing the perforation width beyond xe2x85x9 of an inch can cause food product to hang up and plug the perforations, which then significantly decreases dewatering capacity. Adding more or larger perforations beyond what is presently done causes warping of the bucket. Increasing the thickness of the steel sheet material to permit adding more or larger perforations while attempting to avoid warping also is not the answer because increasing sheet thickness limits the size of each perforation that can be punched. Generally, where the perforations are punched, the size of each perforation can be no larger than 1.5 times steel sheet thickness. The size of laser cut perforations in steel sheeting has generally been viewed as being limited in a similar manner. Additionally, even if it is assumed that these technical difficulties can be overcome, laser cutting is generally less favored than punching because it is more costly and less efficient. As a result, it is generally viewed that increased auger speeds simply cannot be attained using lift buckets of this prior art construction.
What is needed is an improved lift bucket and method of operation that permits increasing auger speeds without increasing loss of liquid from the tank.
The present invention is directed to a food product processing apparatus for processing food product, a food product transport mechanism, a lift used to remove food product from the apparatus, and a method of operating the apparatus where food product processing throughput can be increased while dewatering the processed food products being discharged. A perforate lift comprised of a perforate grid or latticework provides greater open area to increase dewatering at greater food product processing throughput rates.
In one preferred embodiment, the lift is comprised of a plurality of perforate lift buckets that each have at least 24% dewatering open area to provide increased dewatering capacity as compared to prior art lift buckets. Each lift bucket is comprised of grid structure or latticework structure. One such preferred structure includes food product carrying wires that are spaced apart to define dewatering perforations between each pair of adjacent wires. The food product carrying wires are supported by wires that preferably comprise wire retainers that can be clips that engage the food product carrying wires.
In one preferred embodiment, each perforate lift of the invention comprises a lift bucket made of a plurality of pairs of spaced apart and parallel slats that are carried by a plurality of pairs of tie beams. Each tie beam can have an engagement head that engages each slat and underlies a food product-supporting surface of each slat. In one preferred tie beam embodiment, the engagement head has a knife edge that underlies the food product-supporting surface of each slat such that the flow obstruction through each dewatering perforation caused by tie beam interruption is minimized.
A preferred lift bucket construction includes a perforate ramp that increases dewatering surface area. Preferably, both the ramp and a food product-carrying platform are of perforate construction. One preferred lift bucket construction forms the platform of perforate wedgewire. Another preferred lift bucket construction forms the ramp and platform of perforate wedgewire with a bend angling the ramp relative to the platform.
One preferred wedgewire lift bucket construction utilizes parallel screening wires that define dewatering slots that each extend substantially the length of a wire and have a width of between 0.02 inches and 0.13 inches. One preferred wedgewire lift bucket construction utilizes screening wires of generally triangular or frustoconical cross section that have a food product-carrying surface disposed at an angle of at least 2xc2x0. Another preferred wedgewire lift bucket construction utilizes generally triangular wires that have an edge or apex of each wire collectively forming the food product-carrying surface.
A lift bucket of the invention cooperates with a food product transport mechanism of a food product processing apparatus to transport food product to an outlet or discharge while returning liquid food product processing medium to the apparatus. A preferred food product transport mechanism is an auger or helical screw that carries a plurality of the lift buckets. During operation, the auger is rotated to urge food products in the apparatus toward the discharge. The lift buckets are spaced apart and preferably move in concert with the auger or screw. As the food products approach the discharge, a lift bucket lifts one or more of the food products free of the liquid processing medium and transports each food product lifted to a chute of the discharge.
A preferred food product processing apparatus includes a tank that holds the liquid food product-processing medium. The auger is disposed in the tank and the lift buckets are attached to the auger for rotation in unison therewith. During operation, a food product processing apparatus equipped with a plurality of perforate lift buckets of the invention that each have at least 24% dewatering open area rotates the auger at a rotational speed of at least five revolutions per minute without expelling liquid processing medium out the discharge.
Objects, features, and advantages of the present invention include one or more of a perforate lift bucket that has more open dewatering area for greater dewatering capacity; that is stronger and able to transport a greater load of food product to the discharge at a time; that permits faster auger rotation to increase food product processing apparatus throughput while minimizing loss of liquid processing medium; that provides greater dewatering capacity while providing greater strength and torsional rigidity; that is more robust, economical to operate, install and service, and that is long-lasting, can be retrofitted to existing food product processing apparatus installations, and is easy to assemble, install, tune, and use.
Other objects, features, and advantages of the present invention also include one or more of a food product transport mechanism equipped with a plurality of the perforate lift buckets that can be run at a faster speed or rate to increase food product processing throughput; that can be retrofitted to existing food product processing apparatus installations; that can be configured as an auger or screw that is rotated to move the lift buckets in unison therewith at a faster rotational speed; that provides improved dewatering capacity while increasing the weight or mass of food product that each lift bucket can discharge during each auger rotation; that can be economically assembled, tested, shipped and installed including in retrofit applications; and which is simple, flexible, reliable, and robust, and an apparatus which is of economical manufacture and is easy to assemble, install, and use.
Additional objects, features, and advantages of the present invention food product processing apparatus that is equipped with a food product transport mechanism having one or more of the perforate lift buckets that provide one or more of the following advantages, features and/or objects: increases dewatering capacity; increases food product transport mechanism strength and structural rigidity; increases food product transport mechanism speed and processing capacity; and is simple, flexible, reliable, and robust, and which is of economical manufacture and is easy to assemble, install, configure and use.
Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating at least one preferred embodiment of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.